If an Index Fails to Predict Strongly the External Validation

Multiple Choice

If an index fails to predict strongly the external validation items,then

A) the index does not adequately measure the variable in question.
B) the validation items do not adequately measure the variable.
C) either the index does not adequately measure the variable in question OR the validation items do not adequately measure the variable.
D) the index does not adequately measure the variable in question AND the validation items do not adequately measure the variable.
E) you should attempt to use the index anyway to see what will happen.